A new validated score for detecting patient-reported success on postoperative ICIQ-SF: a novel two-stage analysis from two large RCT cohorts

The Patient Global Impression of Improvement (PGI-I) and International Consultation of Incontinence Questionnaire - Short Form (ICIQ-SF) are validated instruments for the assessment of patient reported outcome measures (PROM) following treatment of stress urinary incontinence (SUI). However, there is a paucity of evidence as to what represents a successful postintervention ICIQ-SF score. To determine the correlation between the postoperative ICIQ-SF scores with the PGI-I outcomes, the latter was considered one of the standard PROM following surgical treatment for SUI. The aim of this study was to determine, and if appropriate validate, an ICIQ-SF cut-off score that can predict a successful PROM as determined by PGI-I.

Four large datasets yielding 674 ICIQ-SF score/PGI-I outcome data pairs were used in this study for (a) determining and (b) validating the cut-off ICIQ-SF score for a successful PGI-I outcome. Two long-term follow-up datasets were used representing follow-up periods of 3 and 8 years of a randomized controlled trial (RCT) performed between April 2005 and April 2007 in a tertiary urogynaecology centre in Scotland, UK. All patients had urodynamic SUI or mixed urinary incontinence (MUI, with predominant SUI) and were randomized to treatment with either an inside-out or an outside-in transobturator tape (TVT-O or TOT, respectively) as a sole procedure. The datasets yielded 432 ICIQ-SF score/PGI-I outcome data pairs. Successful outcome was defined as "very much improved/much improved" on the PGI-I scale. SPSS v. 22.0 (IBM Corp., Armonk, NY) was used for all statistical analyses. The correlations and cut-off scores generated were then validated on two independent datasets representing the 1-year and 4-year follow-up periods of the multicentre RCT in six units in the UK. The datasets yielded 242 ICIQ-SF score/PGI-I outcome data pairs. All patients had urodynamic SUI or MUI (with predominant SUI) and were randomized to either adjustable single incision minisling (SIMS) or TVT-O.

Significant correlations at the 0.01 level (two-tailed) were clearly demonstrated between ICIQ-SF scores at follow up and PGI-I outcomes in terms of success/failure in both the generation and validation datasets. Higher ICIQ-SF scores correlated with a 'poorer' PGI-I score. Using ROC analysis, a postoperative ICIQ-SF score of 6 was validated as approximately 90 % sensitive and 85 % specific for success/failure with a high Cohen's kappa coefficient of 0.83 (95 % CI 0.74 - 0.89).

This two-stage study provided a robust well-validated postoperative ICIQ-SF cut-off score (of 6/21) that is likely to be associated with a patient-reported successful outcome on the PGI-I following surgical treatment with a midurethral sling in women at different stages of follow-up over 1 - 8 years. Such a cut-off score could enable the comparison of results between various studies and serve as a valuable guide for surgeons to counsel patients before and/or after surgical treatment. Our study fills a research gap in providing a way to compare trial results when baseline ICIQ-SF scores are not available.

International urogynecology journal. 2016 Jul 05 [Epub ahead of print]

Debjyoti Karmakar, Alyaa Mostafa, Mohamed Abdel-Fattah

Department of Obstetrics and Gynaecology, University of Aberdeen, Aberdeen, UK. ., Department of Obstetrics and Gynaecology, University of Aberdeen, Aberdeen, UK., Department of Obstetrics and Gynaecology, University of Aberdeen, Aberdeen, UK.

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